A German journalist has claimed that Princess Diana was secretly engaged to Egyptian film producer Dodi Fayed before she died in August 1997. Trixi Chall, who wrote for Germany’s popular Bild ­newspaper for two decades, told of a visit to Monte Carlo by Princess Diana and Dodi Fayed – just seven days before the fatal Paris car crash.

Chall claimed that she saw Diana pointing at and picking out a diamond-encrusted ring from an exclusive ­jeweller as they strolled through the resort.

Dodi later arranged for the 11,500 pounds ring – from Repossi the jeweller’s Tell Me Yes range – to be sent to the shop’s sister outlet in Paris. It was then delivered to his suite at the Paris Ritz hotel just hours before the couple died.

The remarkable evidence has added weight to the earlier claims made by former Harrods owner Mohamed Al Fayed that Diana and Dodi were murdered in an Establishment plot to stop the Princess marrying a Muslim.

Chall has now come forward to speak for the first time about the dramatic event she witnessed during an ordinary morning shopping excursion in the swish casino resort of Monte Carlo on Saturday August 23 1997.

On that morning she went to an electrical store by the port. She said that on leaving she glanced across the road and was surprised to see Diana hand-in-hand with a man she had never seen before.

“Nobody else was aware of them and they were aware of nobody, as if they were the only ones in the world. They were not in any hurry, were chatting happily and strolling casually,” the Daily Express quoted her as saying.

Chall, who has detailed her account in a signed statutory declaration, added: “They went to the shop on the left of the Hermitage hotel. They looked in the window and Diana was pointing with her finger at something. I saw them entering the shop.”

There has been much speculation that Diana had an engagement ring when she died after secretly becoming engaged to Mr Fayed.

Chall said she has never given her account to the various investigations because she felt strongly from very early on there was a huge “cover-up of the truth coming from the top”.